Method for winding onto a toroidal core

ABSTRACT

The invention relates to a method of winding a toroidal core ( 1 ) with a wire ( 2 ), wherein the winding of the toroidal core ( 1 ) takes place in a fixed winding plane ( 3 ), and where the toroidal core ( 1 ) is held by a gripper ( 4 ) that moves with it, and is rotated about an axis that is perpendicular to the plane of the ring. The method according to the invention makes it possible to wind even very small toroidal cores having an outside diameter &lt;4 mm.

[0001] The invention relates to a method of winding a toroidal core,where the toroidal core is rotated around an axis that is perpendicularto the plane of the ring.

[0002] Methods of the type named at the beginning are known, in whichthe toroidal core is wrapped in a fixed plane, using a wire magazine.The toroidal core is held between three rollers offset at an angle of120°, and is moved to the appropriate winding position by uniformturning of the rollers.

[0003] This method has the disadvantage that the change in size of thetoroidal core that ensues after the winding process begins, due to theapplied windings, leads to an eccentric position of the core withrespect to the wire magazine. The thicker the wound wire, the greaterthe resulting eccentricity. For this reason, the hole in the center ofthe toroidal core must be significantly larger than the cross-section ofthe wire magazine utilized. Consequently, the known method of windingtoroidal cores, with a resulting remaining hole having the size of theutilized magazine cross-section, is not suitable.

[0004] Furthermore, the known method with the roller drive results inwobbling of the toroidal core during the winding process, which alsorequires the hole in the center of the toroidal core to be larger.

[0005] The objective of the present invention is therefore to specify amethod of winding a toroidal core that makes it possible to wind smalltoroidal cores.

[0006] This objective is achieved according to the invention through amethod of winding a toroidal core according to claim 1. Preferredembodiments of the invention may be found in the other claims.

[0007] The invention specifies a method of winding a toroidal core witha wire, where the winding of the toroidal core occurs in a fixed windingplane. During the winding process, the toroidal core is held by agripper traveling together with the toroidal core, and is rotated aboutits axis, which is perpendicular to the plane of the ring.

[0008] The method according to the invention has the advantage that thetoroidal core is always held firmly by the gripper, independent of thewire wound onto it, and that eccentricities can thereby be avoided. Thewinding of the toroidal core can be carried out, for example, using awire magazine that is also essentially in the form of a ring. During theprocess, the gripper can conduct the toroidal core around the magazinein the clockwise or counterclockwise direction.

[0009] The area on the toroidal core used by the gripper can be keptsmall, and in an advantageous further development of the invention isonly large enough to correspond to the distance between two windingsnecessary for insulation, so that no restriction in the winding of thetoroidal core results from the area taken up by the gripper.

[0010] In another advantageous embodiment of the invention, the grippercovers less than 4% of the circumference of the toroidal core. Thismakes it possible to ensure that there is no restriction on winding thetoroidal core with windings, since a minimum distance must be maintainedbetween the individual windings anyway for reasons of electricalinsulation. If necessary, the gripper can be adjusted to the minimumdistance between two windings, so that any restriction of the windingsby the gripper is precluded.

[0011] It is also advantageous while winding the toroidal core to have athrust bearing positioned in the vicinity of the winding plane, throughwhich the ring can slide, and which absorbs the tensile forces of thewire that arise during the winding process. The thrust bearing isespecially necessary for gripper positions where the plane in which thegripper lies is perpendicular to the winding plane. The moments actingon the gripper, produced by the tensile forces of the wire, are greatestin that case.

[0012] In order to be able to wind the entire circumference of the core,it is advantageous for the thrust bearing to remain engaged with thetoroidal core only until the gripper necessarily approaches the thrustbearing toward the end of the winding process. At that time the thrustbearing can swivel out, and the gripper can produce even further rotarymotion of the toroidal core. That allows the core to be wound almostcompletely. In this gripper position, the bending moments produced bythe tensile forces that act on the gripper are also no longer critical,since the gripper plane is then at only a very small angle to thewinding plane.

[0013] The method of winding a toroidal core can be further improved bycontrolling the gripper by a precise stepper motor. That makes possiblean exact specification of the gradient, that is, the necessary advanceof the toroidal core in relation to the wire diameter, even formulti-layer chokes.

[0014] The method according to the invention has the further advantagethat even extremely small toroidal cores having an outside diameter <4mm, which cannot be wound using the roller bearings, are now accessibleto winding with automatic winding machines.

[0015] In addition, it makes possible the winding of toroidal coreshaving a relatively small center hole, where the winding can be donewith thick wires or a high number of windings.

[0016] With a very small or narrow gripper, the core can be wound overan angle of at least 350°.

[0017] The invention is explained below on the basis of an exemplaryembodiment and the associated figures.

[0018]FIG. 1 shows a schematic representation of an example of a devicefor carrying out the method according to the invention, at the beginningof the winding process.

[0019]FIG. 2 shows a device according to FIG. 1, approximately halfwaythrough the winding process.

[0020]FIG. 3 shows a device according to FIG. 1, toward the end of thewinding process.

[0021]FIG. 4 shows a sectional view through a device according to FIG.1, showing the thrust bearing.

[0022]FIG. 5 shows a sectional view through a device according to FIG.1, showing the gripper.

[0023]FIG. 1 shows a toroidal core 1 in the form of a circular ring,whose top and bottom sides are each bounded by a flat surface. Toroidalring 1 is wound in the fixed winding plane 3 using a wire magazine 6,which is shown in cross-section in FIG. 1, and which extendsperpendicular to the plane of the drawing. The wire 2 wound on the wiremagazine 6 is being wound onto toroidal core 1. Toroidal core 1 is movedby a gripper 4 that holds the toroidal core. The curved arrow indicatesthe direction of rotation of gripper 4. Located on the side of wiremagazine 6, opposite gripper 4, is a thrust bearing 5, which absorbs thebending moments that result from the tensile forces of the wire.

[0024]FIG. 2 shows the device according to FIG. 1, with about half ofthe winding process completed.

[0025]FIG. 3 shows the device according to FIG. 1, shortly beforecompletion of the winding process. In order to be able to wind thelargest possible portion of toroidal core 1, toward the end of thewinding process thrust bearing 5 is disengaged by a movement indicatedby the arrow, so that gripper 4 can continue to move the core 1 in thedirection of winding and can approach close to the winding plane 3. Atthe same time, it assumes the supporting function of thrust bearing 5.In this state, there are also no large bending moments, since the planeof gripper 4 is only at a very small angle to the winding plane 3.

[0026]FIG. 4 shows toroidal core 1 held by thrust bearing 5. Also shownare various positions of the wound-on wire 2. The tensile forces F arealways exerted here in the direction of the wire. They produce a bendingmoment M, which is illustrated by the curved double arrow.

[0027] Toroidal core 1 can be supported in thrust bearing 5 in this caseby means of a ball bearing 7. However, it is also possible to supporttoroidal core 1 in thrust bearing 5 by means of a plastic that allowsslip.

[0028]FIG. 5 shows the toroidal core 1 firmly held by gripper 4, withthe plane of the section lying in the winding plane. In addition, wire 2is shown schematically at various instants during the winding process.The representation of the tensile forces F and of the bending moment Mcorresponds to the representation in FIG. 4. Gripper 4 can consist oftwo halves, which can be removed from toroidal core 1 by pushing themapart in the direction indicated by the double arrow, enabling toroidalcore 1 to be removed after the winding process.

[0029] The invention is not limited to the illustrated exemplaryembodiments, but is defined in its most general form by claim 1.

1. A method of winding a toroidal core (1) with a wire (2), wherein thewinding of the toroidal core (1) takes place in a fixed winding plane(3), and wherein the toroidal core (1) is held by a gripper (4) thattravels along with it, and is rotated about an axis that isperpendicular to the plane of the ring.
 2. The method as recited inclaim 1, wherein a thrust bearing (5) is positioned in the vicinity ofthe winding plane (3), which absorbs the tensile forces (F) that ariseduring the winding process, and through which the toroidal core (1) canslide.
 3. The method as recited in one of claims 1 and 2, wherein thegripper (4) covers less than 4% of the circumference of the toroidalcore (1).
 4. The method as recited in one of claims 1 through 3, whereinthe thrust bearing (5) is removed toward the end of the winding process,in order to allow the gripper (4) to move to the position of the thrustbearing.